Effects of the nanofiller size and aspect ratio on the thermal and rheological behavior of PEG nanocomposites containing boehmites or hydrotalcites

In this work, polyethylene glycol nanocomposites containing different nanofillers (namely hydrotalcites or boehmites, at 5 mass% loading) were prepared by melt compounding. Their morphology and microstructure were assessed by means of SEM and XRD analyses. The interactions between the different nanofillers and the polymer matrix were evaluated by performing rheological, differential scanning calorimetry and thermogravimetric analyses. The two types of nanofillers were found to differently interact with the polymer matrix. In particular, the rheological tests performed on the systems containing hydrotalcites revealed that the presence of nanofillers affects the relaxation dynamics of the macromolecular chains, in a remarkable way. Conversely, the crystallinity degree of the polymer was influenced by the presence of boehmites only, whose nucleating capability was found to depend on their average size. Finally, the thermo-oxidative stability of the polymer matrix was generally improved by the selected nanofillers, with the only exception of the organo-modified hydrotalcite that significantly anticipated the polymer degradation.